Now this is what I'm talking about: a hot and sticky summer. Who needs California, when the sun shines like this in Hackney? My friends Henry and Jemima have a beautiful cherry tree in the back garden of their London Fields home. Probably Morello or Montmorency, their cherries are the sour variety, irresistible when cooked. And I was the lucky recipient of their first crop a couple of weeks ago. A heavy bounty in my bike's basket, I swiftly cycled home to make my favourite summer treat: sour cherry pie.

Sweet cherries are delicious for their cold crisp burst of juice, and are best enjoyed when sitting in a grassy meadow with friends. Did you ever try tying the stem into a knot with your tongue? Supposedly it's the sign of a good kisser. But I digress.

Another wonder about the cherry, is the kernal found inside the stone, called noyau. It is found in all stone fruits. Apricots and peaches are most commonly used, but cherry stones are worth the extra effort involved. Inside the stone, you will find an adorable almond-like core. I think it contains traces of cyanide, so should be used sparingly, but it is one of the most delicious of flavours. A relative of the almond, noyau is a warmer, sweeter version of bitter almond (the variety of almond used to make almond extract, or essense).

I tasted noyau for the first time whilst working at Chez Panisse. During apricot season, we would make a hundred or so tarts a week. Apricot compotes and silky apricot sorbets and ice creams were constantly on the go. All of the stones would be gathered and carried over to the office where the people answering the phones could crack them open all afternoon. They would then come back to the kitchen to be used in making custards and creams.

So get your hands on some backyard sour cherries before the birds get them all. They are all around. You might see a tree that someone isn't using in your neighbourhood. Knock on their door and ask if you can pick some. Make a friend while the sun is still shining. Pretend it's not unusual. Go out on a limb.

The noyau from the centre of two dozen or so cherry stones (see below)

For the pastry:

340g plain flour or "00" type flour from Italy is nice

A pinch of salt

A smidgen of caster sugar

170g very cold unsalted butter cut into 1cm cubes

100ml ice water

egg, lightly whisked with a splash of milk for brushing

For the filling:

500g stoned sour cherries (stones reserved)

150g caster sugar

2 Tbsp corn or potato flour

A pinch of sea salt

1 tsp kirsch (optional)

The noyau from the centre of a dozen cherry stones

Method:

Butter a 9" pie plate and set aside.

Begin by getting your beautiful sour cherries from a friend or supplier you have found, taking them home, and quickly pitting or stoning them as they have a very short shelf life. The little hand-held contraptions I like the best, are the German-made cast aluminium ones with a coating that keeps the metal from reacting. They are sturdy and easy to use. Once you have stoned all of the cherries, you can freeze the fruit or use it right away. If you are lucky enough to have a glut of them, use what you need to make a pie, and freeze the rest.

Lay the cherry stones on a baking sheet lined with parchment paper and place them in a 180°C oven for a few minutes to just dry them out. The main purpose of this is so that your hammer or mallet doesn't slip while you are pounding them open. Place the dried stones in a neat row three inches from the edge of a tea towel. Fold the three -inch length down over the stones and use a hammer or mallet to give each stone a swift blow. Find a rhythm and get cracking. When you have finished, lift the cloth back and carefully select the noyau from the crushed shells. Set about 12 aside for the pie. Take about 24 of them and place in a bowl. Add a tablespoon of sugar and crush them up a bit with the back of a spoon. Pour the single cream over this and cover and chill for at least 6 hours.

Now make your pastry. Place the flour, salt, sugar and butter cubes into a mixing bowl with the paddle attachment and knock it around for a few minutes to break up the butter. A pie pastry should be shorter than the pastry for a galette, so the butter can be mixed in until it resembles a coarse meal. While the mixer is on, drizzle in the cold water and immediately turn it off when the pastry starts to come together into a ball. You must move quickly at this point. Gather the dough together and then divide it into two. Wrap each ball in cling film and them chill for at least 30 minutes.

Meanwhile you can make your cherry filling. Combine all of your ingredients except the noyau and let this sit for a couple of minutes to leech out all the juice from the cherries. Finely chop the noyau.

Preheat your oven to 200° C

The pastry should be ready to roll, so lightly flour a surface and roll to about two - two-and-a-half millimetres thick. Line the pie pan, sprinkle with your chopped noyau, and pour in the filling. Set this in the fridge to chill while you roll out the top half of the pastry. Roll out as above, but using a paring knife, cut one-and-a-half centimetre wide strips. Pull the pie out of the fridge, and arrange in a lattice. Brush with the egg wash, and place in the oven. Bake for about an hour, or until the pastry is golden and the filling is thickly bubbling up through the lattice.

To serve, strain the cream into a jug and pour over hot slices of pie. Mmm.